1. Field of the Invention
The present invention relates to a dental impression material composition to be used for taking an impression of an intra-oral shape for the purpose of preparation of dental prostheses such as a crown, an inlay, and a denture in the dental remedy. In particular, the present invention relates to a dental impression material composition that is superior in affinity with an intra-oral tissue, dimensional precision and storage stability.
2. Description of the Related Art
At present, impression materials made of various materials such as an alginate, agar-agar, silicone rubber, polysulfide rubber, and polyether rubber are used as a dental impression material. Of these, rubber-made impression materials made of silicone rubber, polysulfide rubber, or polyether rubber as a material, which are called rubber-made elastic impression materials, have superior dimensional precision and hence, are used where the precision is required. In particular, a silicone rubber-made impression material is a dental impression material that is most widely used among the rubber elastic impression materials. However, this silicone rubber-made impression material has very high water repellency intrinsic of its material per se. Accordingly, when the silicone rubber-made impression material is to be used for taking an intra-oral part where the water content such as saliva is very high, reproducibility of the details was poor and it is most likely to obtain an incomplete impression. For this reason, in order to improve this defect, silicone rubber-made impression materials comprising a silicone rubber-made impression material to which a surfactant, a polyether-modified silicone oil, etc. are added for the purpose of enhancing the hydrophilicity, are being broadly used. However, there were still involved problems that the hydrophilicity is not sufficient yet such that the reproducibility of the details is incomplete and that a defect likely to be partially generated in the taken impression due to an influence of the water content within the oral cavity.
As the rubber elastic impression material having high hydrophilicity is also known a polyether rubber-made impression material. This polyether rubber-made impression material is different from the silicone rubber-made impression material in that the material per se is a polymer containing a polyether having high hydrophilicity. Accordingly, there is less possibility that, thus not a few impressions become incomplete during the impression taking within an oral cavity. However, the polyether rubber-made impression material is poor in recovery from deformation applied during the time of taking-out from the oral cavity, as compared with the silicone rubber-made impression material. As a result, the polyether rubber-made impression material involved defects that it is deformed, leading to an inaccurate impression to cause a problem in dimensional precision and that it gives a patient an unpleasant feeling due to a peculiar odor and a bitter taste.
As an impression material composition having high hydrophilicity comparable to the polyether rubber-made impression material and having high dimensional precision comparable to the silicone rubber-made impression material, is proposed a curable composition comprising an alkenyl group-terminated polyether and an Si—H group-containing polyether, as disclosed in Japanese Patent Laid-open No. 293955/1992. However, this curable composition is poor in curing properties and storage stability so that it has not yet been put into actual use.